High-quality X-ray spectra of NGC 4636 are obtained with ASCA . Theoretical models are found unable to reproduce the data in the Fe-L line region. Spectral data above 1.4 keV indicate that the Mg to Si abundance ratio is ~1 solar. Assuming that the abundance ratios among α elements are the same as the solar ratios, a spectral fit with increased systematic error in the 0.4-1.6 keV range gives abundances of α elements and Fe to be both ~1 solar by taking 1 solar of Fe to be 3.24 × 10 −5 by number. These new abundance results solve the discrepancy between stellar and hot-gas metallicity, but still a low supernova rate is implied. We also detect strong abundance gradients for both α elements and iron in a similar fashion. The abundance is ~1 solar within 4' and decreases outward down to 0.2-0.3 solar at 10' from the galaxy center. Dilution due to an extended hot gas is suggested.
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Matsushita et al. (1997) studied this question.
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